For five days, from 5 to 9 December 1952, a deathly smog covered London. In some areas, residents faced zero visibility for two entire days. Schools were closed and a performance of the opera La Traviata had to be discontinued because smog obscured the stage. The city ground to a halt. This Pathé film, made in 1953, reminded viewers not only of that appalling event, during which children and even dogs had to be fitted with masks, but that something had to be done about it.

Smog had been a major problem in Britain since industrialisation began, but in the 19th century it had not always been regarded as a public health risk. Indeed, many urban dwellers were more anxious about ‘miasma’ (rotting organic matter and sewage) than sulphurous coal smoke. Some even believed that smoke was a ‘disinfectant’ that could actually protect them against dangerous airborne particles.

By the mid-20th century, however, the link between smog and public health disasters was well established. There was not just a crisis in 1952: smog also caused problems in November 1948 (causing an estimated 700 to 800 deaths), January 1956 (1,000 deaths), December 1957 (750 deaths), January 1959 (over 200 deaths), and December 1962 (between 340 and 700 deaths). It wasn’t just London that suffered in this way. Forty per cent of the population of England lived in ‘black areas’ that experienced severe pollution.

The smog that enveloped London in 1952 was particularly dangerous. At the time, medical officers conceded that 4,000 deaths were directly attributable to it, but recent scholars maintain that there were 12,000 “excess deaths” as a result of those five days and its long-term effects. In typical hyperbolic fashion, the narrator of this Pathé film called smog “one of the greatest mass murderers of all times”.

Why was it so devastating? The winter of 1952 had been particularly melancholic: temperatures had plummeted, so people piled sulphur-rich coal into home-furnaces and fires in an attempt to keep warm. In July, electric trams had been replaced with thousands of diesel-powered buses, leading to unprecedented levels of diesel fumes entering the atmosphere. Industry pumped toxins into the air.

The government had to act. Its Clean Air Act of 1956 granted local governments the power to designate ‘smokeless areas’ in which only authorised smokeless fuels could be burned. As these could not be burned in existing grates, local authorities offered grants to families willing to buy and install the new heating appliances. Slum clearance programs also helped relieve pollution. Most of the houses destroyed were those with old-fashioned coal grates and cooking stoves: local authority houses incorporated gas boilers.

There were major problems with the Clean Air Act: it only addressed visible atmospheric pollution, for instance, ignoring emissions of sulphur dioxide and carbon dioxide. But from 1956 to 1966, smoke emissions from domestic sources fell by 38 per cent: in London, they fell by a whopping 76 per cent. Industrial and railway emissions were reduced by 74 to 92 per cent.

The results were startling. The world became sunnier: the average amount of sunshine in London increased by 73 per cent. The average annual hours of dense fog in central London declined by half. The number of bird species doubled; a wider range of delicate plants survived; and public buildings were much cleaner. Britain’s ‘pea-soupers’, which had inspired novelists and filmmakers for decades, were over.

Joanna Bourke is professor of history at Birkbeck, University of London, and author of What it Means to Be Human (Virago, 2011).

To explore British Pathe’s archive of over 90,000 films from the 1890s to the 1970s go to www.britishpathe.com

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